Detection of fuel contamination in lubricating oil

ABSTRACT

A method for measuring fuel contamination in oil that uses a material in contact with oil whereby fuel intrusion into the oil will change the electrical, mechanical, and/or chemical properties of the material as compared to the same electrical, mechanical, and/or chemical properties of the material when in contact only with mineral or synthetic oil only.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation and claims the prioritybenefit of U.S. patent application Ser. No. 12/857,747 filed Aug. 17,2010, which will issue as U.S. Pat. No. 8,643,388 in Feb. 4, 2014, whichis a continuation-in-part and claims the priority benefit of U.S. patentapplication Ser. No. 12/426,956 filed Apr. 20, 2009, now U.S. Pat. No.7,928,741, which is a continuation and claims the priority benefit ofU.S. patent application Ser. No. 11/676,738 filed Feb. 20, 2007, nowU.S. Pat. No. 7,521,945, which claims the priority benefit of U.S.provisional application 60/782,959 filed Mar. 15, 2006 and U.S.provisional application 60/774,749 filed Feb. 17, 2006, the disclosuresof which are incorporated herein by reference.

U.S. patent application Ser. No. 12/857,747 is related to U.S. patentapplication Ser. No. 08/176,393 filed Dec. 30, 1993, now U.S. Pat. No.5,435,170, U.S. patent application Ser. No. 08/730,109 filed Oct. 15,1996, now U.S. Pat. No. 5,777,210, and U.S. patent application Ser. No.08/637,878 filed Apr. 25, 1996, now U.S. Pat. No. 5,789,665, thedisclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to detecting fuel contaminationin lubricating oil. More specifically, the present invention relates toin-situ fuel contamination detection to prevent catastrophic failure ofengine or other moving parts.

2. Description of the Related Art

Fuel contamination in crankcase oil decreases the lubricating ability ofoil and will lead to engine failure. If a fuel injector becomes stuck inthe open position, the introduction of large amounts of fuel incrankcase oil will decrease the viscosity of the oil. If the fuelcontamination goes undetected, the decrease in viscosity will cause aloss of hydrodynamic lubrication resulting in metal to metal contact andultimately causing spun and/or seized bearings.

Current methods for fuel detection include absorption spectroscopy,viscosity, and the use of a ‘sniffer’ to measure the aromatics in thegas above the oil. Fuel contamination can be detected using absorbancespectroscopy, but the method has been developed for bench topmeasurements after a sample of oil has been removed from the crankcase.The difficulties in applying absorbance spectroscopy to an in-situdevice are significant and make this particular detection techniqueimpractical. Alternatively, and in the absence of other contaminants inthe oil or chemical changes to the oil, fuel (in large enoughquantities) can be detected by measuring the viscosity of the oil bycomparing to the original oil viscosity. However, oil wear, watercontamination, and soot contamination all cause an increase theviscosity of the oil making the detection of fuel contamination in oilby measuring its viscosity difficult. A sniffer requires constantcalibration with a known fuel/oil mixture which is impractical in anin-situ device. Still further, fuel does not significantly change othermeasurable qualities of the oil (conductivity, dielectric constant,resistance, capacitance, polarity, TAN, TBN, etc.) so a direct in-situelectrical or chemical measurement of the oil to detect the presence offuel is difficult.

An in-situ fuel contamination detection sensor is needed for earlydetection of fuel contamination in order to prevent catastrophicfailure.

SUMMARY OF THE PRESENTLY CLAIMED INVENTION

In one embodiment of the present invention, a method for measuring fuelcontamination in oil is disclosed. Through the method, an electrical,mechanical, and/or chemical property of a material in contact with oilis measured. The measured electrical, mechanical, and/or chemicalproperty of the material in contact with the oil is compared against apreviously measured electrical, mechanical, and/or chemical property ofthe same material. A change is identified in the measured electrical,mechanical, and/or chemical property against the previously measuredelectrical, mechanical, and/or chemical property, wherein the changeindicates fuel intrusion into and contamination of the oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the wear of oil due to oxidation and heat whereby theoil becomes more polar as is known in the prior art.

FIG. 2 illustrates an exemplary real-time oil monitoring system as maybe implemented in accordance with an embodiment of the presentinvention.

FIG. 3 illustrates an exemplary embodiment of a sensing element as maybe used in the present invention in addition to an inset reflecting theinstallation of the sensing element in an oil pan.

FIG. 4 is an exemplary illustration of the oil degradation cycle.

FIG. 5A is an exemplary illustration of polymeric bead interaction in anon-polar oil solution representative of relatively low conductivity inan exemplary embodiment of the present invention.

FIG. 5B is an exemplary illustration of polymeric bead interaction in apolar oil solution representative of relatively high conductivity in anexemplary embodiment of the present invention.

FIG. 6A illustrates a single hydrophilic, polystyrene bead in anenvironment without ‘free’ water and reflecting relatively lowconductivity.

FIG. 6B illustrates a single hydrophilic, polystyrene bead in anenvironment with ‘free’ water and reflecting relatively highconductivity.

FIG. 7 illustrates an exemplary interface as may be used with amonitoring device of an exemplary embodiment of the presently disclosedoil monitoring system.

FIG. 8 discloses a method for measuring fuel contamination in oil.

DETAILED DESCRIPTION

Embodiments FIG. 1 illustrates oil that, initially, is clean andnon-polar. In the presence of O.sub.2 and heat, the oil begins todegrade. This application of O₂ and heat would occur through, forexample, the normal and ongoing use of the oil in an automobile. Thispartially degraded oil, as also shown in FIG. 1, begins to take on polarcharacteristics. Through the continued application of O₂ and heat, theoil becomes even more degraded and takes on even greater polarcharacteristics as further shown in FIG. 1. Increased polarity causesthe oil to change is dielectric constant, which in turn leads toincreased capacitance.

FIG. 2 illustrates an exemplary real-time oil monitoring system 200 asmay be implemented in accordance with an embodiment of the presentinvention. An embodiment of the oil monitoring system 200 may comprise amonitoring device 210 for receiving and analyzing data generated by asensing element 220, which is in contact with the oil or other fluidunder observation.

Data generated by the sensing element 220 may be communicated to themonitoring device 210 via a sensor signal cable 230. Sensor signal cable230, in one embodiment of the present invention, is an RS-232 compliantserial cable wherein one end of the cable is configured to exchange datawith the monitoring device 210 and the opposite end of the cable isconfigured to interface with sensing element 220 as is discussed ingreater detail in FIG. 3. Other data cables are within the scope of thepresent invention subject to proper configuration to allow for interfacewith the sensing element 220 and monitoring device 210.

Monitoring device 210 may be further communicatively coupled to anexternal computing device 250 such as a laptop computer, a PDA or othermobile computing device that may be specially configured for use withthe oil sensing element 220 and monitoring device 210. While mobility ofthe external computing device 250 may be preferred in some environment(e.g., a garage), it is within the scope of the present invention forthe external computing device 250 to be a less-portable computing devicesuch as a dedicated workstation or desktop computer. Data may beexchanged between the monitoring device 210 and external computingdevice 250 through, for example, an external data cable 240 or awireless network connection.

External data cable 240 may comply with any number of data transmissionstandards including Universal Serial Bus (USB) and IEEE 1394 in additionto being a parallel or serial data cable. In some embodiments of thepresent invention, monitoring device 210 may be configured for theintroduction of, for example, a PCMCIA wireless card or other wirelessnetwork adapter. In such an embodiment, the monitoring device 210 maycommunicate data gathered from the sensing element 220 as well as dataanalyzed by the monitoring device 210 wirelessly using, for example, the802.11x wireless data standard to external computing device 250 suchthat external data cable 240 is no longer necessary.

A wireless configuration of this nature would allow increased mobilityof the monitoring device 210 while still allowing, for example, for thestorage of oil data in a centralized repository such as theaforementioned external computing device 250. Storage of oil measurementdata and analyses of that data may be useful in determining if aparticular vehicle or combustion engine might be suffering from enginedamage or some other defect in that the particular vehicle or engineprematurely degrades oil. Such information may be reflected by a seriesof oil analyses conducted over time. These analyses may be stored,further analyzed, and graphically illustrated in a report or some otherorganized information presentation generated by external computingdevice 250. It should be noted that the presence of an externalcomputing device 250 is not required for the operation of the monitoringdevice 210 in conjunction with sensing element 220.

The monitoring device 210, in one embodiment of the present invention,receives and displays data indicative of the status of the oil oranother fluid under observation and analysis. The interface ofmonitoring device 210 is discussed in more detail in FIG. 7 below.

Monitoring device 210 and certain devices coupled to device 210 may bepowered by a variety of electrical power sources. In one embodiment ofthe present invention, monitoring device 210 may be electrically coupledto an AC transformer 260. In another embodiment of the presentinvention, monitoring device 210 may be electrically coupled to a DCtransformer such as a cigarette lighter adaptor whereby the system 200may be used ‘on-the-road’ through use of an automobile's cigarettelighter power outlet. Monitoring device 210 may further be powered by areplaceable or rechargeable battery pack (not shown).

In an embodiment of the present invention, the monitoring device 210 mayalso comprise a thermistor configured to be used by a microprocessor inthe device 210 to compensate sensor readings for thermal variations. Forexample, in one embodiment of the present invention, the system 200 mayonly operate at engine operating temperatures in excess of, for example,70° C. as the conductivity of certain oils may be completely masked bythe additives below that temperature. Additionally, because oil isformulated to work at automotive operating temperatures, the oil may notproperly lubricate at lower temperatures thereby distorting datagathered by the sensing element 220.

FIG. 3 illustrates an exemplary embodiment of a sensing element 300 asmay be used in the present invention. The inset of FIG. 3 reflects thesensing element 300 having been installed in an oil pan. Sensing element300 comprises an electrically nonconductive housing 310 with threechambers (320, 330, and 340). Examples of non-conductive materials forconstructing the housing 310 include but are not limited to ceramic,glass, plastic, woven fiberglass, and paper impregnated with phenolicresin (e.g., Pertinax).

In some embodiments of the present invention, the housing 310 may beconstructed of an electrically non-conductive material. In otherembodiments, the housing 310 may instead be constructed of one or morematerials (which may or may not be electrically non-conductive) andsubsequently coated with an electrically non-conductive material such asa non-conductive resin cured with ultraviolet light and/or heat. Inaddition to non-conductive resins, other suitable coating materialsinclude but are not limited to tape, paints and hot melt adhesives.

Housing 310 may be mounted in a conventional drain plug 350 such thatthe sensing element 300 may be installed in a conventional oil pan of aninternal combustion engine. Mounting of the housing 310 may occurutilizing various industrial glues, sealants, adhesives or other meansso long as such mounting means do not interfere with the sensing element300's ability to communicate with cable connector pins 360 as discussedin greater detail below.

By mounting the housing 310 of the sensing element 300 in a conventionaldrain plug 350, an embodiment of the present invention may be installedin older automobiles or equipment utilizing a combustion engines withoutthe need for extensive retrofitting as the drain plug 350 may simply bethreaded into the oil pan's drain hole as would occur when changing theoil of a car. An embodiment of drain plug 350 used for mounting thehousing 310 of the sensing element 300 may utilize ½″×20 threading suchthan an exemplary sensing element 300 measuring approximately 2.8″ inlength occupies an internal depth of approximately 1.8″.

The particular mechanical interface (e.g., shape and threadingspecifications) of the aforementioned drain plug 350 are exemplary asare the particular dimensions of the sensing element 300. The drain plug350 may utilize any variety of physical configurations (e.g., hex nut)and threading arrangements and may further be specially manufactured forparticular combustion engine/oil pan/engine environments. The sensingelement 300 (as a part of or independently of the drain plug 350) mayalso utilize any variety of O-rings, washers, and/or protective housingsin order to properly protect the sensing element 300 and to otherwiseensure that housing 310 is properly secured within the drain plug 350.

One of the three chambers of sensing element 300 (e.g., chamber 320) isopen. Chamber 320 detects the conductivity of the oil directly. Withregard to chamber 320, conductivity is dominated by the ioniccharacteristics of oil additives (oxidation 410) as is shown in theexemplary oil degradation cycle depicted in FIG. 4. In the oildegradation cycle of FIG. 4, as additives are depleted the additivesbecome less polar; as the base oil itself deteriorates, the base oilbecomes more polar.

Returning to FIG. 3, the remaining two chambers (chambers 330 and 340)are covered by a conductive mesh screen (390 a and 390 b). Chamber 330comprises (houses) a matrix of insoluble polymeric beads (not shown).Chamber 340 comprises a single bead (not shown). The conductive meshscreen (390 a and 390 b) may be constructed of stainless steel cloth.

In a non-polar solution with relatively low conductivity, the beads 510Ain chamber 330 remain separate from one another as is shown in FIG. 5A.It should be noted that in FIG. 5A as well as FIG. 5B—for the sake ofsimplified illustration—only a single monolayer of the charged beadmatrix is shown. The fact that only a single monolayer is illustratedshould not be interpreted as otherwise limiting the present disclosure.As the oil's polarity increases, however, the conductivity across thematrix increases and the ionic component of each group of beads relaxes510B and begins electrically interacting with an adjacent group in thepresence of voltage potential. FIG. 5B illustrates the same whereby thebeads form a bridge on the conductive mesh 390 a of the chamber 330. Thechange in the bead matrix as illustrated in FIGS. 5A and 5B indicatesboth additive depletion and oxidation and is represented graphically byline 420 (additive depletion) in FIG. 4.

The sensing element 300 generates a sensor reading reflective ofoxidation based on a differential measurement of a matrix of insolublepolymeric beads and the oil being analyzed. Sensing element 300 furthergenerates a sensor reading reflective of the presence of soot andsimilar contaminants based on a differential measurement of oil inside afilter and the oil being analyzed. Sensing element 300 further generatesa sensor reading reflective of the presence of fuel, water or similarcontaminants based on a differential measurement of a matrix ofinsoluble polymeric beads and the contaminated oil being analyzed. Thesensing element 300 may measure oil quality through the use of any oneof a number of different electrical forms including alternating current(AC), direct current (DC), a combination of AC/DC, in addition tomechanical forms such as crystal resonance. By utilizing sensor readingsfrom the three chambers of the sensor array, an accurate measurement ofoxidation, additive depletion, and contamination is provided, which ismore accurate reflection of oil quality

Data readings from open chamber 320 are subtracted from data readingsobtained from the bead matrix in chamber 330. This subtraction of datamay take place in a differential analysis software module (not shown) inmonitoring unit 210 under the control of a microprocessor (also notshown). Various other hardware and software elements may be present inmonitoring unit 210 to allow for the receipt, processing, analysis,storage, and/or exchange of data. For example, one embodiment of thepresent invention may utilize an application specific integrated circuit(ASIC) for undertaking the differential analysis otherwise performed bythe aforementioned software module. Through the subtraction of the openchamber 320 data, effects of additives are removed from the analysis andonly oxidation is measured. In this regard, no calibration of the system200 is required and any differences in various oil formulations arenegligible with regard to a determination of oxidation in the oil underanalysis.

This differential measurement technique may be used to determine thepolarity of oil where one chamber measures multiple properties of theoil and a second chamber measures the same properties with the exceptionthat it does not measure the polarity of the oil. Taking a differentialmeasurement between the two chambers allows for a determination of thepolar condition of the oil. Specifically, if an electrical measurementof the oil is made and a second electrical measurement is made of anionic polystyrene matrix where the electrical signal includes componentsfrom both the oil and the polystyrene matrix then the difference betweenthe signals shows the polarity of the oil.

Chamber 330 may determine soot contamination in an oil sample whereinthe sensing element 300 has been disposed. Soot particulates consistprimarily of carbon and tend to bind to one another and to the actualengine. If soot is allowed to aggregate unfettered, the sootparticulates can actually begin to score the engine bearings. Sootmeasurement is based on a percentage of the amount of soot freelyavailable in the oil and is commonly referred to as the saturatedrelative contamination. A given amount of free soot can, in someinstances, constitute 1% to 2% contamination for base oil withoutadditives or greater than 7% for fully formulated oils.

When a soot dispersant additive begins to fail, the soot begins toadhere to the surface of the aforementioned polymeric beads and form abridge across the chamber 330. When such a bridge occurs, sensorreadings at chamber 330 change dramatically and continue to increase asmore layers of carbon soot accumulate. Conductivity caused by soot isconsiderably greater than that due to oil and additive polarity and ismeasurable by the present sensing element 300 in addition to capable ofbeing differentiated versus worn oil.

Soot contamination may be determined using a differential measurement.By using two chambers—one that measures the properties of the oil andthe other that measures the properties of the oil after it has passedthru a fine filter that keeps soot or any other contaminates away fromthe sensor—soot contamination can be measured. Specifically, soot thatis not chemically capped is electrically conductive. Taking thedifferential measurement of two chambers where one measures all theelectrical characteristics of the oil and the other is precluded frommeasuring the effect of the soot (or any other particle) in the oil by a0.2 micron filter allows for a determination of soot contamination. Thistechnique is not limited to an electrical measurement; it could also beused in an optical measurement.

The third chamber—chamber 340—may detect water contamination in the oilor fluid under investigation. Water that enters the engine and boils asa result of engine temperature can cause the engine oil to turn into asludge-like substance. This sludge-substance not only fails to properlylubricate various engine components but can also rust an engine from theinside-out.

A determination of water contamination in oil may be made using adifferential measurement technique. By immersing two sensor chambersinto the oil—one that measures multiple properties of the oil and theother measures multiple properties less the property associated withwater contamination—and using a differential technique, the watercontamination may be independently measured. Specifically, if anelectrical measurement of polystyrene matrix is made where the matrix isrelatively insensitive to water contamination and the signal is comparedto a measurement of the polystyrene matrix that is highly sensitive towater absorption, the difference between the measurements will allow thewater contamination to be measured.

The measurement may be made electrically or mechanically by looking atthe change in electrical characteristics of the beads or by looking atthe change in physical characteristics of the beads. Using a highlycross-linked polystyrene matrix will limit both the mechanical andelectrical changes to the bead matrix. Using a loosely cross-linkedpolystyrene bead matrix will allow for large changes in the electricaland mechanical properties of the beads. The change is proportional tothe quantity of water contamination.

Conventional methodologies report water in oil as a percentage of totalvolume. Different blends of oil, however, can consume varying amounts ofwater as a result of oil additives binding with water molecules. Assuch, an absolute measure of water it not necessarily helpful orinformative. An embodiment of the present invention reports watercontent as a percent saturated relative humidity (SRH) of the oil. AnSRH of, for example, 100% where the oil cannot absorb any more waterwithout its dropping out of solution as emulsified or free water is thesame for all oils at a given temperature.

As noted above, a single polystyrene bead 610A in chamber 340 measureswater contamination corresponding to 2% SRH. The diameter of the bead isslightly less than the thickness of the sensor housing/sensor board 310.The bead 610B is extremely hydrophilic and attracts water, swells andphysically contacts the conductive mesh screen 390 b)of the chamber 340.The resulting increase in conductivity is detected as shown in FIGS. 6Aand 6B.

FIG. 6A illustrates a single hydrophilic, polystyrene bead 610A in anenvironment without ‘free’ water and reflecting relatively lowconductivity. FIG. 6B, however, illustrates the same single hydrophilic,polystyrene bead in an environment with ‘free’ water (i.e., watercontamination) whereby the bead 610B swells through its attracting ofthe ‘free’ water and comes into contact with camber 340′s conductivemesh 390 b)thus reflecting relatively high conductivity.

The polystyrene beads of the present invention may be impregnated withcharged groups. In one exemplary embodiment, sodium and sulfite may beutilized as the cation and anion, respectively. Salts of polyatomicanions such as phosphates and carboxylates may also be utilized ascation exchange groups. Additionally, anionic exchange groups maycomprise salts of N-alkylated amines. The beads may be cross linked with8% divinylbenzene and further comprise a titer or exchange capacity of1.7 meq/ml. The beads, further, may be of 1.180 to 38 μm in diameter;500 mg of which being sufficient in the present invention althoughlesser (and greater) amounts are possible in the practice of the presentinvention (e.g., 20 mg).

The beads utilized in various embodiments of the present invention maybe pre-treated or ‘prepared’ in order to create a polar environment thatallows for more accurate measurement of conditions in a non-polarenvironment such as uncontaminated oil solutions.

Such a process may include washing the beads with 1N sodium hydroxidefor approximately 15 to 30 minutes at room temperature; the excesssodium hydroxide is washed off in a methanol bath. The beads are furthersoaked in methanol to remove any excess water and then air dried toremove any remaining methanol. The beads are subsequently soaked inglycerol for approximately 24 hours and then heated to approximately140° C. for approximately two hours to ensure proper penetration of theglycerol. At this point, the beads are fully swollen.

The beads are then placed in a non-polar fluid (e.g., clean oil) andagain heated to 120° C. to remove excess ethylene glycol and to further‘shrink’ the beads to a ‘clean oil’ state. The beads are then loadedinto the various chambers (e.g., 330 and 340) of the sensing element300. The beads are typically loaded into the various chambers (e.g., 330and 340) of the sensing element 300 under slight to moderate pressuresuch that the beads are in close proximity to one another. In analternative embodiment, the beads may be further soaked in glycerol tocause slight expansion of the beads and otherwise obtain bead-to-beadproximity.

Data readings from sensing element 300 are communicated to themonitoring device 210 of system 200 through any number of wire tracings380 on/in the non-conductive housing 310 of element 300. The conductivepathways of the wire tracings 380 are, in some embodiments, etched fromcopper sheets laminated onto the non-conductive housing 310. In otherembodiments, traces may be added through electroplating. Various othermethodologies for creating the conductive wire tracings 380 on thenon-conductive housing 310 including but not limited to silk screenprinting, photoengraving, and milling. In some embodiments of thepresent invention, a series of layers of substrates may make up thenon-conductive housing 310 and a series of blind and/or buried vias (notshown) may be used instead of (or in addition to) surface mountmethodologies.

These conductive pathways are coupled (e.g., through soldering) tochambers 310-340 in addition to output connectors 370, which (in oneembodiment of the present invention) extend outward from the drain plug350 and toward the various elements on the face of the non-conductivehousing 310 of sensing element 300. Output connectors 370 serve tocouple the wire tracings 380 on the face of the non-conductive housing310 to cable connector pins 360 which extend outward from the drain plug350 (and away from the non-conductive housing 310) such that theconnector pins 360 may be connected to sensor signal cable 230 for dataexchanges with monitoring device 210. In this way, data generated at thevarious chambers 310-340 may be communicated through wire tracings 380to the output connectors 370, which connect to cable connector pins 360.

In some embodiments, output connectors 370 and cable connector pins 360may be the same uninterrupted element whereby the pins 360 extendthrough the drain plug housing 350 and toward the non-conductive housing310 where one end of the connectors are soldered to the wire tracings380. In additional embodiments of the present invention, that portion ofthe drain plug 350 most distant from the oil pan or chamber into whichthe non-conductive housing 310 is inserted may have a concave designsuch that the cable connector pins 360 are partially or entirely housedwithin the concave area and protected from damage through exposure tothe elements that might corrode the face of the pins 360 or deform theshape of the pins 360 (e.g., bending) through impact or other appliedforces.

FIG. 7 illustrates an exemplary interface 700 as may be used with amonitoring device 210 of an exemplary embodiment of the presentlydisclosed oil monitoring system 200. After the aforementioneddifferential analysis software module of the monitoring device 210 hasundertaken an analysis of the oil data from sensing element 220, thedata is displayed in an informative format for the user of system 200.

For example, overall oil quality may be reflected by one of a series oflight emitting diodes (LEDs) 710 in the monitoring device 210. Variouslevels of oil quality may be reflected although the present embodimentreflects levels of <good>, <ok>, <fair>, and <change>. The lattersetting—<change>—indicates the poor quality of the oil under analysisand the need for a change of the same.

A similar LED may be utilized to reflect the presence of excess andunwanted soot in the oil under analysis (LED 720) as well as excess andunwanted water (LED 730). These indicators, too, may further orindividually reflect the need to replace motor oil before damage to theengine environment ensues. An overall system status LED 740 indicatesthat the monitoring device 210 and related equipment is in overallworking order and that ‘false positives’ reflecting inaccurate oilreadings are not being generated.

In another embodiment of the present invention, the interface 700 of themonitoring device 210 may reflect a variety of graphical outputs. Forexample, oil quality may be reflected by an LED or digital image outputbar that rises or falls based on the oil quality. Oil quality may alsobe reflected by a digital output reflecting a number indicative of oilquality such that increased quality accuracy is possible.

Data generated as a result of various oil measurements reflects theoverall quality of the oil. For example, normal oil capacitance andnormal oil conductivity in conjunction with no water absorption isgenerally an indicator of overall good oil quality. To the contrary,high oil capacitance, low oil conductivity in conjunction with no waterabsorption may indicate worn oil quality. Low capacitance and lowconductivity of the oil may be reflective of additive depletion. Sootcontamination and water contamination may be reflected by rapidincreases in oil capacitance notwithstanding normal oil conductivity inconjunction with a lack of water absorption and the presence of waterabsorption, respectively.

Various differential measurement outputs (or specific measurements orranges of measurement) may be correlated to the aforementioned interfaceoutputs (i.e., good v. change; graphical bars; numerical output). Insome embodiments, this information may also or, alternatively, bereflected at the external computing device 250.

In some embodiments of the present invention, a series or array of oilsensors 220 may be utilized. The collective measurement data is analyzedby a signal monitoring device 210 or may be collected by individualmonitoring device 210 and subsequently conveyed to the externalcomputing device 250. Through collection and analysis of oil qualitydata from a series or array of oil sensors 220, an even more accurateoil quality reading may be obtained in that irregular and/or inaccurateoil readings (e.g., spikes in data) may be identified and filtered outof the final oil quality analysis. The collective measurement data maybe, for example, batched and collectively analyzed or serially analyzedas data becomes available. Parallel analysis of portions of the oilmeasurement data may also take place.

While the present invention has been described in connection with aseries of exemplary embodiments, these descriptions are not intended tolimit the scope of the invention to the particular forms set forthherein. To the contrary, the present descriptions are intended to coversuch alternatives, modifications, and equivalents as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims and otherwise appreciated by one of ordinary skill in the art.

The aforementioned differential measurement techniques may also be usedfor measuring fuel contamination. Using two sensor chambers—one that issensitive to fuel contamination and one that is not sensitive to fuelcontamination—and taking the differential signal between the two allowsthe for the detection of fuel contamination in oil. This technique isnot limited to the above examples but can also be used to measurespecific additives, contaminates or differences in other types of basestocks. Further, the technique is not limited to measuring electricalproperties. The technique may be used to measure a change in size of apolymeric matrix due to a change in polarity of the oil, change inchemical composition of the oil due to degradation or change in size ofthe matrix due to contamination.

Differential inputs may include beads prepared where one type of beadcan have its ionic group influenced by metals whereas another group willnot be influenced in such a manner. Alternatively, one group of beadsmay be prepared such that they react differently than another group ofbeads in the presence of fuel. Differential measurement combinations maytake into account one or more of different bead types, beadcross-linking, bead size, and bead preparation; the ability to changethe physical properties of the sensor chambers (e.g., filters, electrodesize, electrode shape, and so forth); and electrical excitationpossibilities.

Various embodiments of the present invention may be implemented toanalyze a variety of oil types and viscosities. The present inventionmay be implemented to analyze fluid substances at a variety oftemperatures. The present invention may further allow for retrofittingof older oil pans or combustion engines while further allowing fordesign-specific configurations. In some embodiments of the presentinvention, a sensing element may be dedicated to a particular oilquality determination and used in tandem with a series of other sensingelements with respect to differential measurement of that particularquality or as part of an array with respect to a determining a varietyof qualities utilizing various differential techniques. The presentinvention may be implemented in a variety of different operatingenvironments including but not limited to gasoline engines, dieselengines, transmissions, turbines, transformers, gear boxes, vacuum pumpsand other oil-reliant machinery.

Some embodiments of the present invention may employ various means ofmetal detection. For example, metal detection may be electrical;attaching a specific ion to a polystyrene bead may allow for a specificmetal or group of metals to be detected. In one such example, onechamber of a sensor may contain beads with a hydrogen ion while theother chamber may contain beads with a barium ion. The sensor may beplaced in an oil solution that contains lead whereby the lead woulddisplace the hydrogen ion and electrically ‘cap’ the bead so that itdoes not change conductivity when polarity changes. The barium, on theother hand, would not be affected by the lead and will changeconductivity only when the oil polarity changes. Taking the electricaldifferential of the signals generated by the beads in the two chamberswill provide an indication of the lead contamination.

Metal detection may also be visible. For example, in the presence ofcopper, a colorimetric change takes place when the hydrogen ion isreplaced by a copper ion. While the copper will replace the hydrogenion, the barium ion will not be replaced. Measuring the differential ofthe visible spectra of the two chambers may provide an indication of, inthis example, copper contamination in the oil.

Detection may also occur mechanically or electro-mechanically. The beadsize may change by, for example, 5% when different ions are attached.Using a mechanical differential measurement methodology may provide anindication of specific metals. A spring or fulcrum may be used in someembodiments to show this differential.

In a still further embodiment of the present invention, a method formeasuring fuel contamination in oil uses a material in contact with theoil. Fuel intrusion into the oil will change the electrical, mechanicaland/or chemical properties of the material as compared to the sameelectrical, mechanical, and/or chemical properties of the material whenin contact with mineral or synthetic oil only. The measured property ofthe material that is in contact with the oil/fuel mixture will changewith respect to fuel; oil will not change the property.

In such an embodiment, the material may be a plastic comprised of ahomologous polymer of polystyrene and polyphenylene oxide, which iscommercially available under the brand name Noryl. In anotherembodiment, the material may be a high molecular weight silicone paste.Noryl shows excellent tolerance for mineral oils while showing extremeintolerance (softening) for fuel. Silicone or fluorosilicone paste is anon-polar substance that is susceptible to swelling and even dissolvingin solvents and fuels while the effect of mineral and synthetic oil onsilicone is minimal.

The polystyrene in Noryl can be mixed with other materials either duringpolymerization or post polymerization to enhance its susceptibility tofuel and change its electrical properties. For example, polystyreneco-polymerized and cross-linked with divinyl benzene (DVB) can be used.The amount of DVB used during polymerization can change how theresulting polymer reacts to oil versus fuel. The material could be inthe form of an ion exchange resin bead (e.g., sulfonated or aminatedPolystyrene/DVB) with a chosen substance attached to the ion exchangesites where the fuel will cause a measurable change in electrical,mechanical, or chemical properties of the ion exchange resin bead.Silicone can be doped with different substances to enhance itselectrical properties (e.g., resistance and capacitance), mechanicalproperties (e.g., viscosity and durometry), and chemical properties(e.g., solubility and reactivity).

The material is physically small enough to be placed in some type ofsense element that can be in contact with the fuel/oil mixture in situ.The material could be utilized in a probe. The material (silicone orpolystyrene) could also be in the form of a thin substrate bonded to astiff backbone with two probes on each side (or end) of the substrate.The probes could measure the impedance, capacitance, or resistance ofthe substrate (similar to the thin polystyrene substrate used bymultiple companies to detect water in oil by measuring the change incapacitance of the polystyrene). The probes could be spring loaded wherethe substrate disintegrates in the fuel/oil mixture and the probes wouldform a hard contact.

The system could take the form of a coating that is deposited over aconductive or semi-conductive material causing a change in theelectrical properties or mechanical properties of the system as thephysical or electrical properties of the material change due to thechange in the coating as it comes in contact with fuel.

The material could be in the form of polymeric beads—ionexchange-functionalized or not—where fuel intruding into the oil causesa measurable change in the beads. The beads could be trapped in a meshhousing allowing contact with the oil and the mesh provides a means formeasuring a chemical/electrical/mechanical change in the beads.

FIG. 8 illustrates a method for measuring fuel contamination in oil. Instep 810, an electrical, mechanical, and/or chemical property of amaterial in contact with oil is measured. In step 820, the measuredelectrical, mechanical, and/or chemical property of the material incontact with the oil is compared against a previously measuredelectrical, mechanical, and/or chemical property of the same material. Achange is identified in the measured electrical, mechanical, and/orchemical property against the previously measured electrical,mechanical, and/or chemical property in step 830, wherein the changeindicates fuel intrusion into and contamination of the oil. Theexistence of this intrusion may be reported to a user through aninterface like that described in the context of FIG. 7.

While this invention has been described in conjunction with the specificexemplary embodiments outlined above, many alternatives, modifications,and variations may be apparent to those skilled in the art. Accordingly,the exemplary embodiments of the invention as set forth both areintended to be illustrative and not limiting except as otherwise setforth in the claims.

What is claimed is:
 1. A method for measuring oil quality, the methodcomprising: measuring a property of a material in contact with oil;comparing the measured property of the material in contact with the oilagainst a previously measured property of the same material; identifyinga change in the measured property of the material as compared to thepreviously measured property of the material, wherein the changeindicates fuel intrusion into and contamination of the oil.
 2. Themethod of claim 1, wherein the measured property of the material showsintolerance of the material to fuel.
 3. The method of claim 1, whereinthe material includes polystyrene.
 4. The method of claim 3, wherein thematerial softens in the presence of fuel.
 5. The method of claim 3,wherein the material is Noryl.
 6. The method of claim 1, wherein thematerial includes silicone.
 7. The method of claim 6, wherein thematerial that includes silicone swells or dissolves in the presence offuel.
 8. The method of claim 3, wherein the material is silicone dopedwith other substances.
 9. The method of claim 1, wherein the material isphysically small enough to be placed in a sensing element.
 10. Themethod of claim 1, wherein the material is deposited over a conductiveor semi-conductive material.
 11. A non-transitory computer readablestorage medium having embodied thereon a program executable by aprocessor to perform a method for measuring oil quality, the methodcomprising: measuring a property of a material in contact with oil withone or more sensors in communication with the processor; comparing themeasured property of the material in contact with the oil against apreviously measured property of the same material stored in a datarepository; identifying a change in the measured property of thematerial as compared to the previously measured property of thematerial, wherein the change indicates fuel intrusion into andcontamination of the oil.
 12. The non-transitory computer readablestorage medium of claim 11, wherein the measured property of thematerial shows intolerance of the material to fuel.
 13. Thenon-transitory computer readable storage medium of claim 11, wherein thematerial includes polystyrene.
 14. The non-transitory computer readablestorage medium of claim 13, wherein the material softens in the presenceof fuel.
 15. The non-transitory computer readable storage medium ofclaim 13, wherein the material is Noryl.
 16. The non-transitory computerreadable storage medium of claim 11, wherein the material includessilicone.
 17. The non-transitory computer readable storage medium ofclaim 16, wherein the material that includes silicone swells ordissolves in the presence of fuel.
 18. The non-transitory computerreadable storage medium of claim 13, wherein the material is siliconedoped with other substances.
 19. The non-transitory computer readablestorage medium of claim 11, wherein the material is physically smallenough to be placed in a sensing element.
 20. The non-transitorycomputer readable storage medium of claim 11, wherein the material isdeposited over a conductive or semi-conductive material.